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Hydrogrossular



Hydrogrossular
CategoryMineral Series
Chemical formulaCa3Al2(SiO4)3-x(OH)4x
Identification
Colorgreen to bluish green, pink, white, gray [1]
Crystal habitmassive
Crystal systemcubic [1]
Cleavagenone
Fractureconchoidal [1]
Mohs Scale hardness7 - 7.5 [1]
Lustervitreous
Polish lustervitreous to subadamantine [1]
Refractive index1.810 (+.004, -.020)
Optical PropertiesSingle refractive, anomalous aggregate reaction [1]
Birefringencenone
Pleochroismnone
Ultraviolet fluorescenceinert [1]
Absorption spectradark green hydrogrossular often shows cutoff below 460nm. Other color stones may show line around 463nm, indicating some idocrase content[1]
Specific gravity4.15 (+.05, -.03)[1]

Hydrogrossular, is a calcium aluminium garnet series between the species Grossular and Hibschite Ca3Al2(SiO4)3-x(OH)4x, with hydroxide (OH) partially replacing silica (SiO4).[1] Hydrogrossular is found in massive crystal habit, sometimes grown in with idocrase. [1]

Additional recommended knowledge

Hydrogrossular is translucent to opaque, and found in green to bluish green, pink, white, and gray.[1] The cause of the green color is chromium, and possibly iron.[1] Pink hydrogrossular is caused by the presence of manganese.[1] Hydrogrossular may have dark gray to black small inclusions. [1]It has similarites to jade, and has the misnomers transvaal jade, and african jade.[1]

Hydrogrossular is sometimes used as a gemstone, being cabochon cut, or made into beads. Sources for green and pink hydrogrossular are South Africa, Canada, and the US. White hydrogrossular is sourced from Burma and China.[1]

References

  1. ^ a b c d e f g h i j k l m n o p q Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hydrogrossular". A list of authors is available in Wikipedia.
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